The invention relates to a method for operating a domestic appliance. For at least one operating resource data containing information about a temporal cost profile of the operating resource is received, comprising at least a first time interval with low costs and a second time interval with high costs for the operating resource. A time period of operation of the domestic appliance is compared with the first time interval, in which the costs of the operating resource are low. A time point for the start of operation is determined as a function of the result of said comparison. The invention also relates to a control facility for operating a domestic appliance, which is configured to implement such a method. Finally the invention relates to a domestic appliance having such a control facility.
It is normal for households to have a number of domestic appliances running at the same time, for example a washing machine, dishwasher, tumble dryer and refrigeration appliance. If the domestic appliances run through the respective programs without taking account of the other domestic appliances, a maximum permissible power consumption in the household or in a larger electricity system segment can be exceeded or load peaks can be generated which overload the electricity supply system. This happens for example when high power consumers in different domestic appliances are activated at the same time. Such high power consumers can be for example a heater, an electric motor and a compressor.
So-called intelligent power supply systems or smart grids provide a remedy for uneven load distribution. Such intelligent power supply systems therefore ensure even load distribution in a specified electricity system segment, whether by means of corresponding control commands to electrical appliances or by transmitting information about the temporal profile of energy prices. Energy suppliers are or will be required to offer transparent and flexible tariffs. A domestic appliance can therefore receive data—for example by way of the internet—containing information about the temporal profile of prices for electrical energy (or a different operating resource), in other words information about a temporal cost profile for electrical energy. The domestic appliance can use such information so that for example operation of the domestic appliance is only initiated at a time point when the costs of electrical energy are at their lowest. Such an intelligent procedure can not only relieve the load on the power supply system at certain times of day but it can also reduce costs.
The present invention is based essentially on the subject matter according to publication US 2003/0178894 A1. This document describes a method for controlling the power consumption of an electrical domestic appliance. The domestic appliance receives data containing information about the temporal distribution of the costs of electrical energy. This temporal distribution includes both a time interval with low energy costs and a time interval with high energy costs. Operation of the domestic appliance can only be started when the instantaneous or current time point lies within the low cost time interval. The duration of this time interval is also compared with the time period of operation. Operation is only started on condition that the time period of operation is shorter than the duration of the cited time interval. The method described in the document US 2003/0178894 A1 therefore has the disadvantage that there may be situations in which the time period of operation of the domestic appliance is longer than the duration of the low cost energy time interval. In such instances operation of the domestic appliance cannot be initiated and the domestic appliance does not carry out its actual function.
A washing machine is known from the publication DE 10 2005 055 648 A1, which is configured to prepare hot water. The washing machine contains a water storage unit, which is connected to an external water supply. A control unit controls a process for preparing hot water and communicates with an external unit, which supplies information about energy costs for operation of the washing machine. The process for preparing hot water is activated as a function of the information supplied, specifically when energy costs for operating the washing machine are at their lowest during the course of the day.
An appliance system comprising a plurality of intercommunicating domestic appliances is known from the publication EP 0 727 668 A1. The domestic appliances communicate with one another by way of a communication bus. An overall power consumed by the domestic appliances is measured by a measuring device. The measuring device sends data by way of the communication bus containing information about the current overall power in each instance. Each domestic appliance can tap the same data at the communication bus and set its own power consumption taking into account the information contained in the data. The domestic appliances compare the momentary overall power in each instance with a predetermined limit value. If the overall power exceeds the predetermined limit value, the domestic appliances reduce their power consumption.
In the subject matter according to publication DE 44 46 883 A1 an operator is assisted with the operation of a washing machine in that a distinctive signal is output when a predetermined temperature setting—e.g. 95° C.—is selected. Such a signal informs the operator that the washing process uses a great deal of energy when the selected temperature setting is applied.
A measuring and display device which can be used to measure the power consumption of a domestic appliance is known from the publication GB 2 416 852 A. The measuring and display device comprises a screen, on which the instantaneous power consumption of the domestic appliance is displayed in each instance. The costs of the electrical energy consumed can also be displayed on the screen. The measuring and display device can interrupt operation of the domestic appliance by decoupling the domestic appliance from a supply system when energy costs exceed a predetermined threshold. The measuring and display device can also be integrated in a domestic appliance, specifically in a plug-type facility of the domestic appliance.
The publication US 2008/0015742 A1 describes a system consisting of a plurality of domestic appliances. An apparatus is assigned to each domestic appliance, which serves to generate appliance-specific state data for the respective domestic appliance. Each domestic appliance therefore generates its own state data and transmits said state data to the other domestic appliances. Each domestic appliance also receives the state data of the other domestic appliances. The apparatus processes such state data of its own domestic appliance and the received state data; it then decides—independently of other domestic appliances—whether or not its own domestic appliance is to be brought into operation. The state data includes for example information about the quantity of electrical energy required.
It is known from the publication DE 697 28 496 T2 that the energy consumption of a domestic appliance can be displayed by means of a display facility. Energy consumption can be predicted and displayed on a screen. During a wash process of the washing machine the momentary power consumption in each instance or a total energy consumption of the washing machine is also displayed.
WO 2005/059454 describes a method for defrosting a refrigerator at low cost. With this method information about a low tariff time interval is received from the supplier. It is checked whether an impending defrost operation can be displaced within a tolerance range so that the defrost operation starts in the low tariff time interval. If this is not possible, the defrost operation is still started without consideration of the instantaneously applicable tariff.